It is known from International patent application no. PCT/GB2008/000704 to provide a separation apparatus adapted to maintain a unidirectional flow across a porous filter using a vacuum pump and acoustic standing waves that keep the pores of the filter clear. It has been found by the present Applicant that as the fluid volume retained above the filter reduces, the frequency and amplitude of the acoustics also need to change to prevent blockage of the filter.
U.S. Pat. No. 5,997,490 discloses a system for applying energy to the human body in order to treat bone fractures and osteoporosis by effecting high frequency, low stress stimulation to a fracture or treatment site. The applied energy is such as to cause cyclical displacement or cyclical forces to the bone. There is provided a feedback and control system to apply the energy according to a formula.
US 2007/0249046 discloses a device for ultrasonic treatment, of tissue injuries and to augment the maturation and differentiation of stem cell populations. The device optionally includes a controller with a timer and a display.